Motor With Rotor Positioning Component

ABSTRACT

A motor includes a base, a rotor unit and a driving unit. The base has opposite first and second surfaces. The rotor unit includes a magnet unit disposed on a rotatable magnet carrier to face the first surface of the base. The driving unit includes induction coils disposed on a circuit board, a sensor unit that is disposed on the circuit board and spaced apart from the induction coils and that defines a first reference line with the rotation axis, and a rotor positioning component disposed on the second surface of the base, extending along a second reference line, and capable of magnet attraction with the magnet unit for positioning the rotor unit relative to the sensor unit when the rotor unit stops rotating.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a motor, more particularly to a motor with a rotor positioning component.

2. Description of the Related Art

Referring to FIG. 1, a conventional motor 1 includes a base 11, a circuit board 12, a rotor unit 13 and at least one rotor positioning component 14.

The circuit board 12 has two induction coils 121 and a sensor unit 122. The rotor unit 13 includes a magnet carrier 131 rotatable relative to the base 11, and a permanent magnet unit 132 disposed on the magnet carrier 131. The permanent magnet unit 132 is in a shape of a ring and has a plurality of magnetic pole regions 133 that are angularly disposed with respect to a rotation axis (L) of the magnet carrier 131. Adjacent ones of the magnetic pole regions 133 have opposite magnetic polarities and form a border region 134 that extends radially with respect to the rotation axis (L). Magnetic strength at the border regions 134 is weaker than that at the magnetic pole regions 133. The rotor positioning component 14 is disposed on the circuit board 12 adjacent to the rotor unit 13, and is capable of magnetic attraction with the magnetic pole regions 133 of the permanent magnet unit 132.

The induction coils 121 are operatively associated with the permanent magnet unit 132 to generate a magnetic repulsion force for driving the rotor unit 13 to rotate relative to the base 11 about the rotation axis (L). When the induction coils 121 cease to generate the magnetic repulsion force to stop driving further rotation of the rotor unit 13, the magnetic attraction between the rotor positioning component 14 and one of the magnetic pole regions 133 of the permanent magnet unit 132 prevents the sensor unit 122 from overlapping with a projection of any one of the border regions 134 on the circuit board 12 once the rotor unit 13 stops rotating, thereby facilitating subsequent activation of the rotor unit 13.

However, since the rotor positioning component 14 is disposed between the circuit board 12 and the rotor unit 13, jamming of the rotor unit 13 may occur due to undesired removal of at least a part of the rotor positioning component 14 from the circuit board 12 after long-term use or as a result of vibration of the rotor positioning component 14 when the motor 1 is operational.

Moreover, while modifying the rotor positioning component 14 to be disposed on the base 11 and between the base 11 and the circuit board 12 may alleviate jamming of the rotor unit 13, vibration of the circuit board 12 while the motor 1 is operational may lead to short-circuit between the rotor positioning component 14 and the induction coils 121. While an insulation material may be applied on the rotor positioning component 14 to avoid such short-circuit, additional manufacturing time and costs will be incurred.

Furthermore, even though configuration of the rotor positioning component 14 may prevent the sensor unit 122 from overlapping with a projection of any one of the border regions 134 on the circuit board 12 once the rotor unit 13 stops rotating, the sensor unit 122 may not appropriately overlap with a projection of one of the magnetic pole regions 133 on the circuit board 12. As a result, subsequent smooth activation of the rotor unit 13 may not be guaranteed.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a motor that may alleviate the above drawbacks of the prior art.

Accordingly, a motor of the present invention comprises a base, a rotor unit and a driving unit.

The base has opposite first and second surfaces. The rotor unit includes a magnet carrier and a magnet unit. The magnet carrier is disposed to confront the first surface of the base and is rotatable relative to the base about a rotation axis. The magnet unit is disposed on one side of the magnet carrier and faces the first surface of the base. The magnet unit is in a shape of a ring and has a plurality of magnetic pole regions that are angularly disposed with respect to the rotation axis. Adjacent ones of the magnetic pole regions have opposite magnetic polarities and forma border region that extends radially with respect to the rotation axis.

The driving unit includes a circuit board, a plurality of induction coils, a sensor unit and a rotor positioning component. The circuit board is disposed between the base and the magnet unit . The induction coils are disposed on the circuit board and are operatively associated with the magnet unit to generate a magnetic repulsion force for driving the rotor unit to rotate relative to the base about the rotation axis . The sensor unit is disposed on the circuit board and is spaced apart from the induction coils for detecting the magnetic pole regions. The rotor positioning component is disposed on the second surface of the base and is capable of magnetic attraction with the magnetic pole regions of the magnet unit. A first reference line is defined to extend from the rotation axis of the rotor unit to the sensor unit, the rotor positioning component extends along a second reference line that intersects the rotation axis of the rotor unit, and the first and second reference lines form an acute angle therebetween. Preferably, the acute angle is sufficient to ensure that, when the rotor stops rotating, absolute value of another acute angle formed between the first reference line and the projection of one of the border regions on the circuit board that is closest to the sensor unit is greater than 0 and not greater than 20 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

FIG. 1 is an exploded perspective view of a conventional motor;

FIG. 2 is an exploded perspective view of a first preferred embodiment of a motor according to the present invention;

FIG. 3 is a sectional view of the first preferred embodiment;

FIG. 4 is a schematic view showing a base and a driving unit of the first preferred embodiment;

FIG. 5 is a sectional view of a second preferred embodiment of a motor according to the present invention; and

FIG. 6 is a sectional view of a third preferred embodiment of a motor according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to FIGS. 2 and 3, the first preferred embodiment of a motor 2 according to the present invention is shown to comprise a base 21, a rotor unit 22, and a driving unit 23. The base 21 has opposite first and second surfaces 211, 212. The rotor unit 22 includes a magnet carrier 221 and a magnet unit 223. The magnet carrier 221 is disposed to confront the first surface 211 of the base 21 and is rotatable relative to the base 21 about a rotation axis (L). The magnet unit 223 is disposed on one side of the magnet carrier 221 and faces the first surface 211 of the base 21.

FIG. 4 illustrates the first preferred embodiment without the magnet carrier 221 and with the magnet unit 223 shown in phantom lines. The magnet unit 223 is in a shape of a ring and has a plurality of magnetic pole regions 226 that are angularly disposed with respect to the rotation axis (L). Adjacent ones of the magnetic pole regions 226 have opposite magnetic polarities and form a border region 225 that extends radially with respect to the rotation axis (L). Magnetic strength at the border regions 225 is weaker than that at the magnetic pole regions 226.

Referring to FIGS. 2, 3 and 4, the driving unit 23 includes a circuit board 231, a plurality of induction coils 232, a sensor unit 233 and a rotor positioning component 234. The circuit board 231 is disposed between the base 21 and the magnet unit 223. In this preferred embodiment, there are two induction coils 232 that are disposed spacedly on the circuit board 231 (such as by embedding) and that are operatively associated with the magnet unit 223 to generate a magnetic repulsion force for driving the rotor unit 22 to rotate relative to the base 21 about the rotation axis (L). The sensor unit 233 is disposed on the circuit board 231 and is spaced apart from the induction coils 232 for detecting the magnetic pole regions 226. The rotor positioning component 234 is disposed on the second surface 212 of the base 21 without overlapping with a projection of the sensor unit 233 on the base 21 and is capable of magnetic attraction with the magnetic pole regions 226 of the magnet unit 223.

In this preferred embodiment, the rotor positioning component 234 is an elongate strip made of metal and is attached to the second surface 212 of the base 21, such as with the use of adhesives, and the sensor unit 233 is a Hall element. Specifically, when viewed from the rotor unit 22 as shown in FIG. 4, the sensor unit 233 is disposed on a right-hand side of the projection of one of the border regions 225 and defines a first reference line (D1) with the rotation axis (L) of the rotor unit 22. The rotor positioning component 234 extends along a second reference line (D2) that intersects the rotation axis (L) of the rotor unit 22. A projection of one of the border regions 225 on the circuit board 23 that is closest to the sensor unit 233 is defined as a third reference line (D3). The first reference line and the second reference line (D1 and D2) form a first acute angle (ψ) therebetween which is greater than 30° and less than 45°, and the first reference line and the third reference line (D1 and D3) form a second acute angle (θ) therebetween which is greater than 0° and not greater than 20°.

By configuring the rotor positioning component 234 corresponding to the sensor unit 233, absolute value of the second acute angle (θ) may be controlled to be greater than 0° and not greater than 20° when the rotor unit 22 stops rotating. As a result, the sensor unit 233 is able to correctly detect polarity of a closest one of the magnetic pole regions 226 so as to ensure that the induction coils 232 generate the magnetic repulsion force for driving the rotor unit 22 to rotate relative to the base 21 about the rotation axis (L).

In this preferred embodiment, the sensor unit 233 is disposed on the right-hand side of the projection of one of the border regions 225 and overlaps with the projection of one of the magnetic pole regions 226 so as to detect polarity thereof. This invention should not be limited to such configuration as long as absolute value of the second acute angle (θ) defined by the first and the second reference lines (D1 and D2) is controlled to be greater than 0° and not greater than 20°.

In addition, disposing the rotor positioning component 234 on the second surface 212 of the base 21 is relatively easy, and can prevent jamming of the rotor unit 22 when the rotor positioning component 234 is separated from the base 21. Moreover, direct contact as well as short-circuit between the rotor positioning component 234 and the circuit board 231 can be prevented because of the base 21 that is made of an electrical insulating material. As a result, additional manufacturing time and costs will not be incurred, and operational stability and production efficiency of the motor 2 will be improved.

In order to prove the effect of this invention, an experiment was conducted to energize the motor 2 under different second acute angles (θ). The result of this experiment is shown in Table 1, wherein the second acute angle (θ) with a positive value was defined from the third reference line (D3) to the first reference line (D1) in a clockwise direction, and the second acute angle (θ) with a negative value was defined from the third reference line (D3) to the first reference line (D1) in a counterclockwise direction.

Referring to FIG. 4 and Table 1, as the absolute value of the second acute angle (θ) increases, the required voltage for driving rotation of the rotor unit 22 increases as well. The motor 2 was unable to work when the absolute value of the second acute angle (θ) was greater than 40°. The motor 2 was sometimes vibrating when the absolute value of the second acute angle (θ) was greater than 20° and smaller than 40°. The motor 2 was working without any vibration when the absolute value of the second acute angle (θ) was greater than 0° and not greater than 20°. Therefore, the result demonstrates that the rotor unit 22 is successfully driven if the absolute value of the second acute angle (θ) is controlled to be greater than 0° and not greater than 20°. In addition, the required voltage for driving rotation of the rotor unit 22 is lower when the absolute value of the second acute angle (θ) is controlled to be greater than 0° and not greater than 15°.

TABLE 1 Revolution Electric Required Per Minute Current Voltage No θ (rpm) (mA) (V) Remark 1  45° — — — Not working 2  40° — — — Not working 3  35° 11790 34 3.8 Vibrating 4  30° 11850 34 3.5 Vibrating 5  25° 11790 33 3   Vibrating 6  20° 11800 33 2.4 Working 7  15° 11700 32 1.9 Working 8  10° 12000 32 1.8 Working 9  5° 11700 32 1.6 Working 10  −5° 11900 32 1.5 Working 11 −10° 11800 32 1.5 Working 12 −15° 11810 32 1.7 Working 13 −20° 11700 33 2.3 Working 14 −25° 11900 34 2.9 Vibrating 15 −30° 11810 34 3.5 Vibrating 16 −35° 11700 34 3.9 Vibrating 17 −40° — — — Not working 18 −45° — — — Not working

Referring to FIG. 5, the second preferred embodiment of the motor 2 of the present invention is similar to the first preferred embodiment. The difference resides in that the rotor positioning component 234 is an elongate strip embedded in the second surface 212 of the base 21 so as to prevent separation between the rotor positioning component 234 and the base 21.

Referring to FIG. 6, the third preferred embodiment of the motor 2 of the present invention is similar to the first preferred embodiment. The difference resides in that the rotor positioning component 234 is an elongate strip having two bent end parts 235 that engage a periphery of the base 21 and that help prevent separation between the rotor positioning component 234 and the base 21. Each of the bent end parts 235 has a tip that does not extend beyond the first surface 211 of the base 21 so as to prevent contact between the rotor positioning component 234 and the circuit board 231.

To sum up, by configuring the rotor positioning component 234 corresponding to the sensor unit 233, absolute value of the second acute angle (θ) may be controlled to be greater than 0° and not greater than 20° because of the magnetic attraction between the rotor positioning component 234 and the magnet unit 223 when the induction coils 232 cease to generate the magnetic repulsion force to stop driving further rotation of the rotor unit 22. In other words, the magnetic attraction between the rotor positioning component 234 and the magnet unit 223 ensures overlap between the sensor unit 233 and a projection of one of the magnetic pole regions 226 on the circuit board 231 when the rotor unit 22 stops rotating. As a result, the sensor unit 233 is able to correctly detect polarity of the magnetic pole region 226 so as to ensure that the induction coils 232 generate the magnetic repulsion force for facilitating subsequent activation of the rotor unit 22. Furthermore, disposing the rotor positioning component 234 on the second surface 212 of the base 21 can prevent jamming of the rotor unit 22 when the rotor positioning component 234 is separated from the base 21. Moreover, direct contact as well as short-circuit between the rotor positioning component 234 and the circuit board 231 can be prevented because of the base 21 that is made of an electrical insulating material. As a result, operational stability and production efficiency of the motor 2 will be improved.

While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

What is claimed is:
 1. A motor comprising: a base having opposite first and second surfaces; a rotor unit including a magnet carrier disposed to confront said first surface of said base and rotatable relative to said base about a rotation axis, and a magnet unit disposed on one side of said magnet carrier facing said first surface of said base, said magnet unit being in a shape of a ring and having a plurality of magnetic pole regions that are angularly disposed with respect to the rotation axis, adjacent ones of said magnetic pole regions having opposite magnetic polarities and forming a border region that extends radially with respect to the rotation axis; and a driving unit including a circuit board disposed between said base and said magnet unit, a plurality of induction coils disposed on said circuit board and operatively associated with said magnet unit to generate a magnetic repulsion force for driving said rotor unit to rotate relative to said base about the rotation axis, a sensor unit disposed on said circuit board and spaced apart from said induction coils for detecting said magnetic pole regions, and a rotor positioning component disposed on said second surface of said base and capable of magnetic attraction with said magnetic pole regions of said magnet unit such that, when said induction coils cease to generate the magnetic repulsion force to stop driving further rotation of said rotor unit, the magnetic attraction between said rotor positioning component and said magnet unit prevents said sensor unit from overlapping with a projection of any one of said border regions on said circuit board once said rotor unit stops rotating; wherein a first reference line is defined to extend from the rotation axis of said rotor unit to said sensor unit, said rotor positioning component extends along a second reference line that intersects the rotation axis of said rotor unit, and the first and second reference lines form an acute angle therebetween.
 2. The motor as claimed in claim 1, wherein the acute angle is sufficient to ensure that, when said rotor stops rotating, absolute value of an angle formed between the first reference line and the projection of one of said border regions on said circuit board that is closest to said sensor unit is greater than 0 and not greater than 20 degrees.
 3. The motor as claimed in claim 1, wherein said rotor positioning component is an elongate strip attached to said second surface of said base.
 4. The motor as claimed in claim 1, wherein said rotor positioning component is an elongate strip embedded in said second surface of said base.
 5. The motor as claimed in claim 1, wherein said rotor positioning component is an elongate strip having two bent end parts that engage a periphery of said base, each of said bent end parts having a tip that does not extend beyond said first surface of said base. 